Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include<bits/stdc++.h>
using namespace std;
#define M 1000000000
int h,w,cnt;
char c[52][52];
vector<vector<int>> a(52,vector<int>(52,M));
int dx[4]={1,-1,0,0},dy[4]={0,0,1,-1};
queue<pair<int,int>> q;
void bfs(int i,int j){
  for(int k=0;k<4;k++){
    if(c[i+dx[k]][j+dy[k]]=='.'){
      if(a[i][j]+1<a[i+dx[k]][j+dy[k]]){
        a[i+dx[k]][j+dy[k]]=a[i][j]+1;
        q.push(make_pair(i+dx[k],j+dy[k]));
      }
    }
  }
}
int main(){
  cin>>h>>w;
  for(int i=1;i<=h;i++){
    for(int j=1;j<=w;j++){
      cin>>c[i][j];
      if(c[i][j]=='#'){
        cnt++;
      }
    }
  }
  a[1][1]=1;
  bfs(1,1);
  while(!q.empty()){
    bfs(q.front().first,q.front().second);
    q.pop();
  }
  if(a[h][w]==M)cout<<-1;
  else cout<<h*w-a[h][w]-cnt;
}